1. Field of the Invention
The present invention relates to radio communication devices and radio communication terminals, and, more particularly, to a radio communication device and a radio communication terminal preferably for use in an RFID (Radio Frequency Identification) system, for example.
2. Description of the Related Art
In recent years, RFID systems have been used as information management systems for products in which transmission of predetermined information is performed in a non-contact manner between a reader/writer for generating an induction field and an RFID tag (hereinafter also referred to as a radio communication device) attached to a product. The RFID tag includes a radio frequency IC for storing predetermined information and processing a predetermined radio signal and an antenna for transmitting/receiving a high-frequency signal.
International Publication No. WO2007/083574 discloses a radio frequency IC device used in an RFID system. This radio frequency IC device includes a feeding circuit board on which a radio frequency IC chip is mounted. The feeding circuit board is coupled to a radiation plate (antenna pattern) primarily via a magnetic field. In the radio frequency IC device, the frequency of a transmission/receiving signal is determined by a feeding circuit included in the feeding circuit board. Accordingly, an operating frequency does not depend on the size of the antenna pattern and a material used for a device supporting member, and provides a stable frequency characteristic.
International Publication No. WO2007/083574 further discloses an example of a radio frequency IC device in which a feeding circuit board on which a radio frequency IC chip is mounted is disposed on the surface of a resin film on which an antenna pattern is provided. In this device, the antenna pattern includes a loop pattern, and the feeding circuit board is disposed at the center of the loop pattern. The antenna pattern and an inductor pattern in the feeding circuit board are magnetically coupled to each other. When a metal body is disposed in or close to a region in which the magnetic field is provided, the metal body interferes with the formation of the magnetic field. As a result, a communication range may be reduced or communication may be significantly deteriorated. When the position of the feeding circuit board deviates from the center of the loop pattern, a frequency characteristic may be changed.